1. Field of the Invention
The present invention relates to electrical contacts for use with semiconductor devices. The electrical contacts of the present invention may be used to provide temporary electrical connections as semiconductor devices are being burned in or otherwise tested. More specifically, the present invention relates to electrical contacts which include stereolithographically fabricated portions. The present invention also includes semiconductor devices, carriers, probe cards, and other substrates that employ such electrical contacts. Additionally, the present invention includes methods relating to fabrication of the electrical contacts of the present invention and structures incorporating same.
2. Background of Related Art
Numerous types of electrical contacts that are configured to provide temporary communication between the bond pads or other contacts of a semiconductor device and corresponding terminals or other contacts of a test substrate, carrier substrate, or other electronic component have been developed and used in the art.
Several examples of temporary electrical contacts have been developed by FormFactor, Inc., of Livermore, Calif., and are described in U.S. Pat. No. 5,476,211, as well as in other U.S. patents referenced hereinbelow that have been assigned to FormFactor (hereinafter collectively “the FormFactor Patents”). Each of these temporary electrical contacts is a compressible, resilient element which is secured to a bond pad of a semiconductor device. They may include a core and an outer coating, both of which are formed from electrically conductive materials. The core may comprise a relatively soft material, or material which is subject to plastic deformation, while the outer coating may comprise a more rigid material, which imparts the electrical contact with elastic properties. Alternatively, the core may be formed from a more rigid, elastic material, while the coating is formed from a material that enhances adhesion of the electrical contact to a bond pad of a semiconductor device.
The electrical contacts that are described in the FormFactor Patents are represented to be useful for providing temporary electrical connection between the bond pads of a semiconductor device and the contacts of a test or burn-in substrate. They may also provide permanent electrical connections between the bond pads of the semiconductor device and corresponding contacts (i.e., bond pads, terminals, leads, etc.) of another semiconductor device, a carrier, another semiconductor device component, or another electronic device.
The FormFactor Patents teach that wire-bonding apparatus may be used to form the core of an electrical contact of the type described therein, while conventional deposition or plating methods may be used to coat each core with another layer of conductive material. As conventional wire-bonding apparatus are typically configured to form only a single conductive element (e.g., bond wire, electrical contact, or other conductive structure) at a time, and since there may be thousands of bond pads on a substrate (e.g., silicon wafer) upon which numerous semiconductor devices are carried, the electrical contact fabrication processes that are described in the FormFactor Patents may be extremely and undesirably time consuming. Furthermore if, as described in the FormFactor Patents, gold is used to form the cores of numerous electrical contacts, the cost of forming the cores may be extremely and undesirably expensive.
The contacts described in the FormFactor Patents may be used, for example, in probe cards, which are used to establish a temporary connection between a semiconductor device and a test substrate or burn-in substrate. The contacts are positioned at locations that correspond to the locations of corresponding bond pads of the semiconductor device and terminals of the test substrate or burn-in substrate. Thus, the contacts are positioned so as to align between corresponding bond pads and terminals when the probe card is aligned between the semiconductor device and the test substrate or burn-in substrate. The compressibility of such contacts imparts the probe card with dimensional tolerance for the spacing between the semiconductor device and the test substrate or burn-in substrate.
Whether the Form Factor contacts are used with a probe card or another type of semiconductor device component, they may be compressed or deformed beyond their elastic limits, which will render them useless.
Accordingly, processes are needed by which electrical contacts may be more efficiently and cost-effectively fabricated, as are electrical contacts that are formed by such processes, protective structures for preventing damage to such electrical contacts, and semiconductor devices, carriers, probe cards, and other substrates with which such electrical contacts may be assembled.